A needle free access valve is one where the valve can be opened using a needleless syringe. A needleless syringe is a syringe where the needle has been removed such that the front of the syringe has only the luer taper or luer lock. Such valves are known but suffer from a number of disadvantages.
A serious disadvantage with many existing one-way valves is that fluid can flow back into the valve from the body cavity or the body in which the needle etc has penetrated. This results in contamination, and a potential health hazard. Most valves are provided with some form of spring or bias to naturally bias the valve back into the closed position.
In our earlier international patent application PCT/AU02/00861 there is described a one way valve that delivers a positive pressure to prevent backflow. In this valve arrangement, there is provided a sliding plunger which is connected to a biasing web and movement of the plunger stretches and retracts the web. The web forms part of a variable volume chamber to keep a positive pressure.
One disadvantage with this valve and with most other one-way valves used in the medical area is that the valve typically contains a sliding plunger that slides between the open position and the closed position. The sliding plunger is typically biased back to the closed position. Insertion of a luer tip or other type of device into the inlet of the one-way valve pushes the sliding plunger against the bias to the open position. Therefore, the plunger cannot move to the closed position until the luer tip or other device has been removed from the inlet. Thus, when the fluid flow through the device ceases, the plunger remains in the open position (and therefore backflow is not prevented) until such time as the luer tip or other device has been removed from the inlet. This can create circumstances where a small amount of backflow can still occur, or where there is a time delay between the fluid flow ceasing, and removal of the tip or other device from the inlet of the one-way valve (which then allows the plunger to move to the closed backflow prevention position).
Therefore, there would be an advantage if it were possible to provide a one-way valve that may contain parts that move between an open position and a closed position (for instance such as described in our earlier PCT application listed above) but which can also contain some form of valve or sealing member that is operable between a open fluid flow position and a closed position by the action of fluid. An advantage of this is that as soon as the fluid flow stops, the valve can move to the closed position before any further parts of the valve move (e.g. the plunger). The valve can be in addition to the ordinarily moving parts of the one-way valve, or can replace at least some of the ordinarily moving parts of the one-way valve.
Another disadvantage with backflow prevention valves is that there is still the possibility of blood finding its way ultimately close to the inlet of the valve which can be a source of hazard. Therefore, there would be an advantage if it were possible to provide a one-way valve that could reduce or eliminate this occurrence.